Major Findings There are no results to report as yet since we have only recently started data collection. Proposed Course of Work The overarching hypothesis guiding this work is that stimulating the brain via the spinal pathways with fast repetitive muscle activation over a prolonged period will lead to changes in the degree of connectivity across brain regions. Unfortunately, we will not have the temporal resolution to evaluate changes in timing of the cortical responses, but this may be inferred by the changes in the cognitive and motor response speeds, assuming these occur. If response speed does increase, future studies using imaging techniques with greater temporal resolution would be indicated. We are including sophisticated balance assessments as well as dual task assessment paradigms here that we anticipate will be particularly sensitive measures in this population. We are including similar measures in other NIH TBI protocols including the RMD Screening Protocol (Chan: PI) and the chronic TBI Longitudinal Cohort Study (Chan: PI) and potentially the Breecher Study (Grafman: PI). This will yield a wide-range of patients with balance and brain imaging data that will enable us to decipher some of the potential mechanisms for balance disorders in this population. From this, targeted clinical trials to specifically address balance disorders can be initiated. Dr. Cristiane Zampieri-Gallagher will most likely lead these future investigations under my mentorship. Project Impact Statement This project has the potential to contribute to our fundamental understanding of brain injury as well as lead to new treatments to enhance motor and/or psychological well-being and promote neural recovery in those with TBI. A novel intervention is proposed that has been shown some level of efficacy in other populations with related disorders. The use of fast speed elliptical training is based on recent evidence on the fundamental role of exercise in neural repair and recovery of function across multiple brain subsystems (motor, sensory, cognitive, emotional, etc.). This project also has strong relevance to the intent and mission of the CNRM which is to create bridges across federal institutional efforts to advance the scientific study of traumatic brain injury, with a specific interest in the potential for neural plasticity and recovery of pre-injury functioning.